I purchase an inexpensive AMECO Morse Code Straight Key and needed a way to keep its Bakelite base from flopping around while keying.
I pride myself on repurposing items I have around the house. My wife's old laptop with a shattered LCD screen is now being repurposed and controls my model train layout with the addition of a monitor. I had recently purchased a treadmill, the packing included two sturdy steel mounts to hold the base of the treadmill in one place during shipment. I held on to these mounts thinking at some point they would come in handy. Well one these mounts in going to be repurposed as a base for my AMECO Morse Code Straight Key! Below is a picture of the soon to be repurposed steel mount.
Machining the Steel Mount
The steel mount is shaped like an capital "L" the short side will be pressed up against the side of the table in my Radio Shack. I decided to secure the morse code straight key as far up the long part of the steel mount as possible so as to give my hand a place to rest on. I drilled two holes in the mount so that I can securely mount the key with screws.
The bottom side of the steel mount was a little rusty as it had not been painted. Afterall, it was only intended to be part of the treadmill's packaging to be discarded after assembly. I used some fine grit sandpaper to remove the rust, degreased the surface then teated it of a little black paint.
Add some feet
I added four self-adhesive feet to the bottom so as to prevent the base from skidding around on the table and to prevent the table from marring the freshly painted surface.
The last step was to permanently mount my straight key to the new base.
Two nuts along with lock washers hold the straight key to its new base.
Putting the straight key into production
Here is a picture of my Morse Code Straight Key, with newly constructed base, connected to my homemade 80M CW Transmitter. Time to make some QRP contacts!
My father-in-law, AKA "The old man from California" loves hunting for bargains at flea markets and garage sales in his so-cal neighborhood. If he finds something interesting and Amateur Radio related, he'll ship it back east to me so I can take a look at. My father-in-law knows I enjoy the challenge in getting vintage radio equipment working again. He couldn't resist purchasing this Yaesu FT-411 2M Transceiver for a couple dollars at a garage sale and shipping it to me to see if I could repair it.
The Yaesu FT-411 was a popular 2M FM Transceiver from the late 1980s and early 90s. It boasted up to 5 Watt RF Power Output with the 12Volt 600mAh ni-cd battery pack installed! The one my father-in-law sent me had the mobile PA-6 DC-Adapter/Charger installed but not the required "Wall-Wart" AC Adapter. I was, however, able to power the FT-411 up using my variable DC bench power supply. Surprisedly, the FT-411 powered up but some of the indicators in the LCD screen did not display as they are supposed to in receive mode. In addition, the FT-411 would not transmit and it would "forget" the frequency I was on turned off and back on.
Remove Bottom Plate
Time to disassemble the FT-411 in order to troubleshoot the issue. Slide the PA-6 DC-Adapter/Charger or battery pack sideways to remove, this will expose four screws on the bottom of the radio. There are a lot of small screws holding the FT-411 Transceiver together so I recommend keeping a set of jeweler's screwdrivers handy. Remove the four screws, circled in red, then remove the bottom plate.
Remove Top Cover
Disconnect the antenna, then remove the four screws that hold the top cover in place. Remove the waterproof membrane, shown in the picture below, after the top cover has been removed.
Opening the Case
The sides of the case are held in place with one screw on each site (circled in red in the picture below). Once removed the FT-411 opens up in clam-shell fashion. The printed circuit board on the left is the RF board and handles the sending/receiving of radio signals. The printed circuit board on the right is the microprocessor board that handles display functions and controls the RF board.
I desoldered one side of the copper shield, used to protect the processor from RF energy, and pulled it back so I could get a closer look at the processor board.
While examining the processor board, I noticed some sloppy soldering work across several semi-circle solder pads (circled in red in the picture below). This was unlike the neat solder work across the rest of the board. Through some Internet research I found a site containing information about modifying the FT-411. I have determined that bridging these pads with solder alters the behavior of FT-411 Transceiver. The processor determines the state, open or close, upon power up and uses this information to determine operability. It looks like the previous owner of this FT-411 tried to modify the operation of this transceiver by soldering/unsoldering the pads but he/she did not do in a pattern that this transceiver would recognize. It was my hypothesis that this botched modification job prevented the FT-411 from working properly. I de-soldered all bridges but across terminal 3, this is the factory default setup.
It is a good idea to test a fix, before completely assembling a transceiver. I connected the battery terminals leads, observing the polarity, via alligator leads to my DC bench power supply and raised the power up to 7.2volts. In addition, I used another alligator lead as an antenna. SUCCESS! Indicators on the LCD panel display properly in receive mode and I was able to transmit! Although, I still had the issue where the FT-411 would not remember my frequency setting when turned off then back on.
3V Lithium Battery replacement
The FT-411 uses a 3V Lithium Battery (circled in the picture below), in order to retain configuration settings in it's volatile memory, when not powered on. Most likely, this battery is already marginal or dead after 25 years of service. Having your FT-411 "forget" the frequency you were on with each power cycle is a good indication that this battery has failed! You will need to remove the processor board from the case in order to replace this coined shaped battery. I circled the locations of the screws for processor board removal below.
3V Lithium Battery replaced!
Amazon had a suitable replacement 3V Lithium Battery with solder tabs. The battery was intended as a replacement for the first generation Nintendo Gameboy but suits my purpose just fine. Do not try to purchase a 3V Lithium Coin battery without solder tabs then try to solder leads to it. The heat will ruin the battery. Below is a picture of new 3V Lithium Battery install on the processor board.
To reassemble, follow the disassembly steps in reverse order, make sure you reattach the insulator using a dab of hot glue to ensure that the battery does not short out on the metal shielding of the RF board. See are circled in the picture below.
Sometimes the fix to a complex transceiver system can be as simple as a dab of solder in the wrong place, as in the case of this Yaesu FT-411 repair. One of the most important troubleshooting tools a Amateur Radio Enthusiast has is his/her eyes, ears, and sense of smell. In this case the only tool I needed were my eyes. It was a real joy to get this old Yaesu FT-411 functional again!
I love reading old ARRL (American Radio and Relay League) publications. ARRL is an amateur radio advocacy group started in 1914 and based in Hartford Connecticut. Through the years they have also published many books on different amateur radio subjects. The current vintage ARRL publication I am reading is "How to become a radio amateur" from 1961. This was and still is a great publication. It teaches a newly minted Amateur Radio enthusiast practical skills and also includes plans on how to build your very own Regenerative Short Wave Receiver, Continuous Wave Transmitter, and a Power Supply to power both Receiver and Transmitter. You typically can find such vintage ARRL publications at flea markets, Hamfests, or in Amazon used books!
"Boat Anchor" is an endearing term used to described old, obsolete Amateur Radio equipment. Typically this equipment was heavy and cumbersome due to the large transformers needed to convert the AC line voltage into the proper DC high voltages required for the vacuum tubes to operate. The equipment is so heavy it can be used as a boat anchor!
Here is the latest edition to my "Boat Anchor" collection, a YaesuMusen FT-401B from the early 1970s. This rig is a hybrid, meaning that it uses transistors to handle many of the lower power tasks. Back in the early 1970s transistor technology was not up to the task of handling high power duties so transmitter output in the FT-401B is achieved using vacuum tubes.
The YaesuMusen FT-401B supports AM, SSB, and CW modulations and is capable of 560 W (PEP input) using SSB and 430 W (input) using CW without the assistance of a linear power amplifier!
Eventually the YaesuMusen name was shortened to Yaesu for the US market. This rig is a great addition to my collection and I look forward to repairing it and getting it back to original spec!
I have built many regenerative vacuum tube shortwave receivers, now I wanted to attempt to build a simple shortwave transmitter.
While searching on the Internet, I came across an article from "The Heart of Texas DX Society" about building a simple one tube transmitter using a common 6L6 Power Beam Tetrode Tube. This got my creative juices flowing and I decided this will be my first vacuum tube transmitter project!
The 6L6 Transmitter I am to build is that of CW (Continuous Wave) type. A CW transmitter conveys intelligence in the form of Morse Code dots and dashes by turning on and off the transmitter. It does not convey the spoken word using AM (Amplitude) or FM (Frequency) modulation. CW is the oldest way of conveying information by wireless.
The 6L6 Transmitter is basically a crystal controlled radio frequency oscillator. C1, Coil, and C2 form a tuned matching circuit used to match the high impedance of the oscillator circuit to the low impedance of the antenna. The 2.5 MH choke connected in series between the 300 Volt DC Power Supply and the Plate (pin 3) of 6L6 prevents RF from feeding back into the power supply. The Crystal and 2.5MH choke connected in parallel connected to the grid (pin 5) forms a frequency stable oscillator circuit that is amplified by the 6L6 tube. This oscillator circuit is controlled by the Key switch, which opens and closes the path to ground for the 6L6 tube amplifier circuit thereby stopping and starting the oscillation and RF output. The 220 ohm 1Watt resistor in series with the cathode (pin 8) acts as a current limiting resistor.
The crystal and coil can be changed in the circuit so that the transmitter can be used on the 40 meter or 80 meter Amateur radio bands.
At the time of the writing I only had a 6V6 tube and power output was only 5 Watts. I expect a power output of at least 25 Watts once I replace the 6V6 tube with a 6L6!
Below is a reprint of the schematic from "The Heart of Texas DX Society" web site article written by James Tobola - KC5LDO
Step 1 Enclosure Build
I chose a classic "L" design for the enclosure. It is made from pine I salvaged from a shelf in the garage. It took quite a bit of effort to remove the oil and grease stains. I then used a palm sander to smooth out the imperfections. The front is held in place by three wood screws.
Step 2 Front Panel Parts Placement
My next step was to determine where to place the controls on the front panel. I placed the Plate and Load variable capacitors next to each other as it is important to keep wire connections in the RF section as short as possible so as not to introduce stray inductance into the mix.
Step 3 Drilling the Front Panel
The shafts of the variable capacitors, selector switch, and key jack, are too short to connect through the 3/4 width of the front panel. I used a Wooden Hole Saw Set to drill concentric holes 1/2 deep into the back of the front panel so that the shafts would protrude from the front.
Step 4 Bottom Panel Parts Placement
I created a paper template that showed parts placement and mounting holes. I then used a metal punch to transfer the hole placement to the top of the bottom panel. In addition, I including wiring information on paper template.
Wood Putty Saves the Day!
Four of the holes used to mount the standoffs are counter-sunk. I accidentally made the holes the larger diameter of the screw head. This is were a little wood putty saved the day!
Step 5 Dry Fit Parts
I mount all of the parts to the wooden chassis and check the fit before applying a protective layer of Polyurethane.
Step 6 Winding the Coils
The 6L6 Transmitter uses two interchangeable coils mounted to a tube base. One coil is for 40M band operation, the other is for the 80M band.
Step 7 Mounting the Crystal
I also mount the appropriate crystal in the tube base so switching bands is a one step operation.
Step 8 Final Finish
I apply two coats of Polyurethane followed by sanding with a fine grit sandpaper. I then apply a final coat.
Step 9 Apply Foil Coating
I had a lot of problems with hand capacitance modifying the operation of the regenerative radios I built. As such, I glue aluminum wrap to the back side of the front panel and tie to ground in order to hopefully reduce this issue.
Step 10 Final Assembly
I can now permanently mount the parts to the wooden chassis, now that the Polyurethane coating has been applied and the foil backing has been applied to the front panel.
Step 11 Installing Mounting Feet
I install mounting feet to the corners of the bottom of the bottom panel. This prevents the bottom from getting scuffed up when being moved. How many times can I use the word bottom in a sentence ;-)
Step 12 Filament Wiring
I wire the connections to the tube filament first.
Step 13 Ground Wiring
Next I wire all connections tied to ground.
Step 14 All Other Wiring
Then I wire everything else!
Step 15 Install Vacuum Tube and Coil, label connections
The next step is to install the vacuum tube and the coil.
Step 16 Install knobs, label front panel
The final step in the assembly process is to install the knobs and label the front panel.
Step 17 Initial Testing
I use an Heathkit HP-23A to provide the 6.3 Volts AC filament and 300 Volts DC required for operation of the 6L6 Transmitter. I had to open up the HP-23A and jumper to the proper Voltage connections as I do not have the power output cable that comes with this power supply.
I also connected I Digital Multimeter in order to monitor the voltages during operation.
The 6L6 Tube Transmitter in Operation!
See my 6L6 CW Vacuum Tube Transmitter in operation. Please note that I did not have a 6L6 Vacuum tube on hand and used a 6V6 tube instead. As such, the transmitter power output was only about 5 Watts.
This was a most gratifying project. When not in use it is proudly displayed on a shelf in my basement "Man Cave". Building a 6L6 CW Transmitter is a great way to learn about the electronics of the past.
My attempt on using reclaimed wood, salvaged from our near centennial house, in a project. I am not sure what caused this wood to darken but I love the look!
Much like the familiar Healthkit, Hallicrafters offered amateur radio kits from 1938 until the early 1970s when Japanese competition made the electronic kit building building business unprofitable. This is a fine specimen of Hallicrafters S-40S shortwave receiver from the 1940s that I recently acquired and plan on restoring over the winter.
What is a Doerle Short Wave Set?
Doerle "sets" were a popular home built regenerative shortwave receiver of the 1930s. Designed by amateur radio enthusiast Walter C. Doerle of Oakland, California. Doerle's regenerative radio designs were published in many amateur radio magazines in the 1930s. Doerle's Short Wave Set designs were so popular in the 1930s because of the ease of construction and use of inexpensive parts in their design.
Not much is know about Walter C. Doerle or if he was even compensated for the designs featured in the book "How to build 4 Doerle Short Wave Sets" and other vintage publications.
The Doerle name lives on as his shortwave set designs are still popular with Glowbug and Boat Anchor amateur radio enthusiasts of today.
Regenerative Receiver: Type of receiver that feeds a portion of the output signal back to the input, in a positive feedback configuration, in order to boost the amplitude of a radio signal many times.
Glowbug: Term used by amateur radio enthusiasts to describe a simple home built tube-type radio set, reminiscent of the shortwave radio craze of the 1930s.
Boat Anchor: Obsolete tube type radio sets that are so heavy and cumbersome that they could be used as a boat anchor!
It's the 21st Century, can I still purchase vacuum tubes?
Absolutely, there are many vendors that sell vacuum tubes and high voltage electronic components required for vacuum tube circuits. Many musicians and audiophiles even today love the sound of vacuum tube audio amplifiers as they believe they produce a warmer more natural sound. As such, there are many vendors that cater to their vacuum tube needs.
The type 30 vacuum tubes and other components used in the Doerle Short Wave Set I built are available from the two vendors below.
Source of Vacuum Tubes and related components
Building a Two Tube Doerle Shortwave Receiver Set
Step 1 Source Vacuum Tubes and Electronic Parts
I found everything required to build my Two Tube Doerle Shortwave Radio set from Antique Electronic Supply (AES), the link to this company's web site was provided earlier.
Step 2 Design and Build Cabinent
The cabinet is made of salvaged wood from shelves that used to hang in my garage. I used degreaser to remove motor oil from the surface. Once degreased and dry, I used a palm sander to smooth out dents and imperfections.
The cabinet for my Doerle Shortwave Receiver is going to be open type. Basically, L shaped with the top piece used as the front panel with all of the controls, and a bottom where the majority of parts are to be placed.
The shafts for the Tuner, Regeneration, and Filament controls are not long enough to protrude through the front of the 3/4 inch wood. So I decided to carve out areas in the wood so that the shafts could protrude through the front.
Next, it was time to layout the parts on the front panel and bottom of my Doerle Shortwave Receiver. I then mount parts with screws and checked for fit and placement.
I used tape to mark the depth of holes I want to drill so as not to drill right through the wood.
I used a Wooden Hole Saw Set to drill concentric holes 1/2 deep into the back of the front panel.
I then used a screwdriver like a wood chisel to remove the remaining wood between the concentric holes drilled by the Hole Saws.
This is how the back of the front panel looks after the remaining wood was removed from the indentations created. The indentations were then sand to remove any roughness.
I created a paper template to be used later to plan out the wiring.
Time for two coats of polyurethane with light sanding between each coat!
I glue aluminum foil, the same type you use to wrap food in, to the back of the front panel. Elmer's White Glue works fine. This foil will be tied to circuit ground in order to reduce the effects of hand capacitance during operation.
Finally, some rubber feet on the back side of the bottom panel.
Step 3 Final Mounting of Electronic Parts
It is easiest to mount the variable capacitors and variable resistor to the front panel first!
Finally, you can mount the hardware on the bottom panel.
Step 4 Wiring
Creating a wiring diagram a head of time makes wiring easier.
Here is my Doerle Shortwave Receiver ready for wiring.
First, I wired all of the ground connections (Black wires).
Next the 90 Volt circuit (Purple wires)
Followed by the tube filament circuit (Red wires).
Finally the 45 Volt and Tuning circuits (Yellow and Blue wires).
Step 5 Winding the Coils
The coil that is part of the tuning tank circuit, and the regenerative coil, are mounted to a removable 8-pin octal base. You plug in different coil assemblies into the octal socket on the bottom panel of the radio to change Shortwave Bands.
Here is a picture of the coil assembly for the 15-45 Meter Bands.
Next you have to scrap off the varnish insulation on the 22# magnet wire in order to prep for soldering.
Next you feed the bare part of the magnet wire through the proper pins and solder.
Here is top view of the coil assembly.
Finally, check each coil's continuity at the pins.
Step 6 Final Prep
Install the Type 30 Triode Tubes, plug the coil into the socket, label connections.
In addition, label the front controls and headphone connections.
Step 7 Obtain Suitable Power Supply
In my "Battery Box", I use two D batteries for the 2 Volt filament voltage. I connect many 9 Volts in series to obtain the 90 and 45 Volts needed to power the receiver.
Fahnesstock Clips on the back of the "Battery Box" provide access to the required Voltages.
Connect the Doerle Shortwave Receiver to a suitable power supply, antenna and ground. I use my external G5RV Amateur Radio antenna and main water pipe that comes into our house as a ground. In addition, connect high impedance headphones to the front.
Front view showing the Tuning, Filament, and Regeneration controls. In addition, connections for headphones.
Step 9 Testing
Set the Tuning, Filament, and Regeneration controls to mid position. You should hear atmospheric "hiss" from the headphones, once the power supply, antenna, and ground are connected. Use the Tuning knob to select AM broadcasts. Once selected, adjust the Regeneration control counter-clockwise to the point of where you hear oscillation, then turn it clockwise slightly until the oscillation stops and the AM broadcast is clear.
This is the point that the Doerle Shortwave Receiver is at maximum gain. Turn the Regeneration control further clockwise to reduce receiver gain if the AM broadcast is overpowering the headphones. The only time you should need to adjust the Filament control is if your A+ batteries is getting weak. Adjust the control until there is 2 Volts at the filament pins of the Type 30 vacuum tubes.
Here are some troubleshooting tips if your Doerle Shortwave Receiver is not working as expected.
No sound from headphones:
This was a most gratifying project. When not in use it is proudly displayed on a shelf in my basement "Man Cave". Building a Doerle Receiver is a great way to learn about electronics past.
Who Writes This Blog?
John is an IT professional from Cleveland, OH who enjoys amateur radio, ham radio, metal detecting,
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